From 881d693c8603510bee3b88205a90ca97942ee0b9 Mon Sep 17 00:00:00 2001
From: Erik Westrup <erik.westrup@gmail.com>
Date: Wed, 26 Mar 2014 15:23:31 -0700
Subject: [PATCH] cmd/go: Use exported CgoLDFlags when compiler=gccgo

If you compile a program that has cgo LDFLAGS directives, those are exported to an environment variable to be used by subsequent compiler tool invocations. The linking phase when using the gccgo toolchain did not consider the envvar CGO_LDFLAGS's linking directives resulting in undefined references when using cgo+gccgo.

Fixes #7573

LGTM=iant
R=golang-codereviews, iant
CC=golang-codereviews
https://golang.org/cl/80780043
---
 src/cmd/go/build.go  |  1 +
 src/cmd/go/test.bash | 25 +++++++++++++++++++++++++
 2 files changed, 26 insertions(+)

diff --git a/src/cmd/go/build.go b/src/cmd/go/build.go
index 6166410c6e..a21c873c85 100644
--- a/src/cmd/go/build.go
+++ b/src/cmd/go/build.go
@@ -1905,6 +1905,7 @@ func (tools gccgoToolchain) ld(b *builder, p *Package, out string, allactions []
 	ldflags = append(ldflags, afiles...)
 	ldflags = append(ldflags, sfiles...)
 	ldflags = append(ldflags, cgoldflags...)
+	ldflags = append(ldflags, p.CgoLDFLAGS...)
 	if usesCgo && goos == "linux" {
 		ldflags = append(ldflags, "-Wl,-E")
 	}
diff --git a/src/cmd/go/test.bash b/src/cmd/go/test.bash
index fe00df9e24..1091695b37 100755
--- a/src/cmd/go/test.bash
+++ b/src/cmd/go/test.bash
@@ -669,6 +669,31 @@ if ! ./testgo test -c -test.bench=XXX fmt; then
 fi
 rm -f fmt.test
 
+TEST 'Issue 7573: cmd/cgo: undefined reference when linking a C-library using gccgo'
+d=$(mktemp -d -t testgoXXX)
+export GOPATH=$d
+mkdir -p $d/src/cgoref
+ldflags="-L alibpath -lalib"
+echo "
+package main
+// #cgo LDFLAGS: $ldflags
+// void f(void) {}
+import \"C\"
+
+func main() { C.f() }
+" >$d/src/cgoref/cgoref.go
+go_cmds="$(./testgo build -n -compiler gccgo cgoref 2>&1 1>/dev/null)"
+ldflags_count="$(echo "$go_cmds" | egrep -c "^gccgo.*$(echo $ldflags | sed -e 's/-/\\-/g')" || true)"
+if [ "$ldflags_count" -lt 1 ]; then
+	echo "No Go-inline "#cgo LDFLAGS:" (\"$ldflags\") passed to gccgo linking stage."
+	ok=false
+fi
+rm -rf $d
+unset ldflags_count
+unset go_cmds
+unset ldflags
+unset GOPATH
+
 # clean up
 if $started; then stop; fi
 rm -rf testdata/bin testdata/bin1
-- 
2.50.0